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A frame from an animation showing an induced pressure gradient that generates a shock wave that strikes the interface separating two gas mixtures. The initial shock wave reflects off the wall at the end of a tube and strikes the interface again. This re-shock leads to enhanced turbulent mixing; a second shock wave further destabilizes the interface separating the two gas mixtures. (Image: Victor Zendejas Lopez.)

Victor Zendejas Lopez worked on cars before he realized that his interests went far deeper under the hood. After high school, he sold auto parts, worked as a mechanic and eventually pursued an engineering degree at University of California, Berkeley, with the goal of designing automobiles. But as an intern at General Motors and Intel, he realized that he was more interested in studying fundamental processes within burning fuels using computational fluid dynamics.

Instead of pursuing a career at GM, he took a third internship at Lawrence Berkeley National Laboratory and developed algorithms for high-performance computers. Today Zendejas Lopez brings those interests together as he simulates turbulence at Caltech and in collaboration with Lawrence Livermore National Laboratory, supported by a Department of Energy Computational Science Graduate Fellowship (DOE CSGF).

During his Ph.D., Zendejas Lopez has modeled hydrodynamic instabilities, the tiny, cumulative interactions in mixing fluids that lead to a chaotic buildup of turbulence over time. Fluids fall into two distinct categories, Zendejas Lopez says: fully compressible like the air we breathe, or incompressible like water. He studies turbulence in these different fluids and has simulated how shock waves influence compressible flows.

“It’s very intellectually stimulating to study turbulence,” he says, “because there are so many different ways of looking at it.”

Zendejas Lopez started with incompressible flows and the Kelvin-Helmholtz instability. Found in the atmosphere and in supersonic combustion, this flavor of turbulence occurs where two fluids moving at different velocities meet and form wavelike whorls.  After working on this system with his Ph.D. advisor Guillaume Blanquart, Zendejas Lopez became curious about computational approaches to study turbulence in compressed fluids, pursuing that interest through DOE CSGF practicum research at Livermore.

In summer 2023, he worked with Robert Rieben simulating the Richtmyer–Meshkov instability, a process that occurs when two fluids with different densities are compressed, often via a shockwave. This process is the primary instability in fusion fuels and can divert critical energy needed to drive fusion reactions.

At Livermore, Zendejas Lopez’s simulations model the turbulence that occurs as shockwaves move through tubes of mixing fluids, results that inform laboratory experiments. Ultimately this understanding could improve the design of fusion fuel capsules, which could boost the energy yield from these reactions.

Zendejas Lopez returned to Livermore in 2024 and extended this work with Rieben and Dan Meiron with further Richtmyer-Meshkov simulations under various shockwave conditions. He’s also working to speed up turbulence simulations and boost their efficiency without sacrificing accuracy. Toward that goal, he’s exploring numerical methods that incorporate approximations, algorithms that incorporate faster graphics processing units and can compute turbulence statistics on the fly, reducing the need to store large amounts of turbulence simulations.

His collaboration with Livermore continues, and Zendejas Lopez plans to return to the lab for a third practicum in 2025. After graduation, he hopes to work at a national lab.

Zendejas Lopez overcame multiple challenges to pursue a research career. Although he grew up in the United States, he was undocumented until high school and struggled academically. His parents could not read or write.

He relied on mentors and programs such as the Princeton Pathways to Graduate School to find his path into research. Zendejas Lopez now mentors undergraduates in that program and first-year graduate students at Caltech.

“I try to give back as often as I can,” he says. “Without the constant support and mentoring, I wouldn’t be here today.”